1. Field of the Invention
The present invention generally relates to an apparatus and a method for supporting a Universal Serial Bus (USB) multicast.
2. Description of the Related Art
FIG. 1 illustrates an example in which a teacher lecture terminal distributes identical electronic class data to a plurality of student class terminals.
Peripheral devices connected to a host system may use a serial port, a parallel port, a Universal Serial Bus (USB) port, or the like as a communication channel through which data is transmitted and received.
The host system may be referred to as, for example, the teacher lecture terminal 100. The peripheral devices may be referred to as, for example, the student class terminals 110, 112, 114, 116 and 118.
As shown in FIG. 1, when the identical electronic class data is distributed from the teacher lecture terminal 100 to the plurality of student class terminals 110, 112, 114, 116, and 118 in a classroom, a total time for transmitting the electronic class data to all of the student class terminals 110, 112, 114, 116, and 118 is proportional to the number of the student class terminals. Because a USB port provides only a unicast, the teacher lecture terminal 100 should form a one-to-one connection with each of the student class terminals 110, 112, 114, 116, and 118, and sequentially and separately transmit the electronic class data.
Therefore, a method for quickly transmitting an identical file from the teacher lecture terminal 100 to all of the student class terminals 110, 112, 114, 116, and 118 is required.
FIG. 2 illustrates a layer structure diagram of a host and a device based on a WSB.
The WSB refers to a technique of wirelessly connecting a Universal Serial Bus (USB) host with a USB hub/USB device using a wireless (Wi-Fi) link. The WSB may recycle the existing mass storage supporting a USB device (a Mass Storage Class (MSC)) and a Multimedia Transfer Protocol (MTP).
In addition, the WSB is a simple protocol based on a non-Internet Protocol (IP), and is suitable for a simple file transmission performed in an independent classroom/meeting room.
Referring to FIG. 2, a host 200 includes a USB host layer 202, a host Protocol Adaptation Layer (PAL) 204, a Wi-Fi Media Access Control (MAC)/Physical (PHY) layer 206. The device 210 includes a USB device layer 212, a device PAL 214, a Wi-FI MAC/PHY layer 216. The host PAL 204 is an adaption for using the USB host layer 202 on the Wi-Fi MAC/PHY layer 206. The host PAL 204 changes a control signaling and data used in a USB host to a message or performs an inverse operation.
The USB host layer 202 and the USB device layer 212 transmit and receive USB data through an End Point (EP) 1 208 and an EP1 218. The EP1 218 of the USB device layer may be an identifier of a data tunnel used in a USB layer.
In addition, the host PAL 204 and the device PAL 214 performs a signaling through an EP a 209 and an EP a 219.
FIG. 3 illustrates a structure diagram of an existing host and devices.
Referring to FIG. 3, a host 300 transmits and receives USB data to and from a device 400 and a device 500 through a USB port.
At this time, a USB_EP_1 308-1 of the host 300 is mapped with a USB_EP_1 408-1 of the device 400, and a PAL_EP_1 309-1 of the host 300 is mapped with a PAL_EP_1 409-1 of the device 400.
In the same manner, a USB_EP_2 308-2 of the host 300 is mapped with a USB_EP_2 508-2 of the device 500, and a PAL_EP_2 309-2 of the host 300 is mapped with a PAL_EP_2 509-1 of the device 500.
Therefore, as described above, since the teacher lecture terminal 100 should form a one-to-one connection with each of the student class terminals 110, 112, 114, 116 and 118 and sequentially and separately transmit the electronic class data, a file transmission time is proportional to the number of the student class terminals.